| Group leader [message #13083] |
Wed, 14 October 1998 00:00  |
Imanol Echave
Messages: 26
Registered: May 1998
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Junior Member |
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Hi people:
I have a little question: What is the difference between the GROUP_LEADER
keyword on XMANAGER and the same keyword used on a top-level base? Do they work
on the same way?
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| Re: Group leader [message #13175 is a reply to message #13083] |
Wed, 14 October 1998 00:00  |
David Foster
Messages: 341
Registered: January 1996
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Senior Member |
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Imanol Echave wrote:
>
> Hi people:
>
> I have a little question: What is the difference between the GROUP_LEADER
> keyword on XMANAGER and the same keyword used on a top-level base? Do they work
> on the same way?
Imanol -
As far as I know, they serve the same purpose. the GROUP_LEADER
keyword to WIDGET_BASE() is more recent, and it's my impression
that it is "preferable" to use the keyword here rather than in
the XMANAGER call.
I have a modal popup information widget that just comes up and
says "Please wait...busy doing < >...", and then after some processing
the widget is killed by the calling module. In this case, since this
widget doesn't generate any events, you don't register it with
XMANAGER. But I *do* want it to have a GROUP_LEADER, so I declare
it in the call to WIDGET_BASE() for the popup widget.
Dave
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
David S. Foster Univ. of California, San Diego
Programmer/Analyst Brain Image Analysis Laboratory
foster@bial1.ucsd.edu Department of Psychiatry
(619) 622-5892 8950 Via La Jolla Drive, Suite 2240
La Jolla, CA 92037
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
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| Re: Group leader [message #13196 is a reply to message #13083] |
Sat, 24 October 1998 00:00 |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Imanol Echave (ccaeccai@sc.ehu.es) writes:
> I have a little question: What is the difference between the GROUP_LEADER
> keyword on XMANAGER and the same keyword used on a top-level base? Do they work
> on the same way?
In this case it doesn't matter at all whether you assign
the group leader to the top-level base with the GROUP_LEADER
keyword when you create the TLB or when you call XMANAGER,
but this is not always the case with the TLB. For example,
you should never use the EVENT_PRO keyword to assign the
event procedure to a TLB; always use the EVENT_HANDLER
keyword on XMANAGER. Similarly, you should never use the
KILL_NOTIFY keyword to assign a clean-up routine to the
TLB; always use the CLEANUP keyword on XMANAGER.
Failure to heed these warnings causes some VERY strange
behaviour in widget programs. And the warnings in the
documentation are worded in such a way that many people
miss them. :-)
Cheers,
David
----------------------------------------------------------
David Fanning, Ph.D.
Fanning Software Consulting
E-Mail: davidf@dfanning.com
Phone: 970-221-0438, Toll-Free Book Orders: 1-888-461-0155
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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